Effect of acute exposure to settleable atmospheric particulate matter emitted by the steel industry on hematology and innate immunity of fat snook (Centropomus parallelus).

The steel industry is a significant worldwide source of atmospheric particulate matter (PM). Part of PM may settle (SePM) and deposit metal/metalloid and metallic nanoparticles in aquatic ecosystems. However, such an air-to-water cross-contamination is not observed by most monitoring agencies. The region of Vitoria City is the main location of iron processing for exports in Brazil, and it has rivers, estuaries, and coastal areas affected by SePM. We have evaluated the effects of SePM on a local representative fish species, the fat snook, Centropomus parallelus. After acclimation, 48 fishes (61.67 ± 27.83 g) were individually exposed for 96 h to diverse levels of SePM (0.0, 0.01, 0.1 and 1 g/L-1). The presence of metals in the blood and several blood biomarkers were analyzed to evaluate the impact of SePM on stress signaling, blood oxygen transport capacity, and innate immune activity. Metal bioaccumulation was measured from blood in two separately analyzed compartments: intracellular (erythrocytes plus white blood cells) and extracellular (plasma). The major metals present at all contamination levels in both compartments were Fe and Zn, followed by Al and Cu, plus traces of 'Emerging metals': Ba, Ce, La, Rb, Se, Sr, and Ti. Emerging metals refer to those that have recently been identified in water as contaminants, encompassing rare earth elements and critical technology elements, as documented in previous studies (See REEs and TCEs in Cobelo-García et al., 2015; Batley et al., 2022). Multivariate analysis revealed that SePM had strong, dose-dependent correlations with all biomarker groups and indicated that blood oxygen-carrying capacity had the highest contamination responsiveness. Metal contamination also increased cortisol and blood glucose levels, attesting to increased stress signaling, and had a negative effect on innate immune activity. Knowledge of the risks related to SePM contamination remains rudimentary. However, the fact that there was metal bioaccumulation, causing impairment of fundamental physiological and cellular processes in this ecologically relevant fish species, consumed by the local human population, highlights the pressing need for further monitoring and eventual control of SePM contamination.

Toxic risk evaluation of effluents from a swine biodigester in the plant models Lactuca sativa and Allium cepa.

Pig farming is recognized as an activity with great polluting potential. The aim was to investigate possible environmental risks of effluents from the stabilization pond (SP) and the raw effluent (RE) from the biodigestion process of swine residues, in different concentrations in the models Lactuca sativa and Allium cepa. Seeds were germinated in different dilutions, 100% (C1), 50% (C2), 25% (C3), 12.5% (C4), 6.25% (C5), 3.12% (C6), 0.78% (C7), and 0.39% (C8). Distilled water was used as the negative control (CN) and trifluralin (0.84 g/L-1) as the positive control. Germination (GR), root growth (RG), cell cycle, and oxidative stress (OS) were analyzed. To assess OS, the activity of the enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST) and the quantification of glutathione (GSH) and lipid peroxidation (LPO) were analyzed. Data were submitted to ANOVA (one way), followed by the Kruskal-Wallis mean test (P ≤ 0.05). Chemical analysis showed high values of Cu, Fe, Mn, and Zn. Dilutions (C1, C2, C3 RE) and (C1 and C2 SP) inhibited GR and RG of L. sativa and A. cepa than other concentrations. The mitotic index showed a reduction in C5 (RE), C6, and C7 (SP) of L. sativa and C3 and C4 (SP) of A. cepa in relation to CN and higher frequencies of chromosomal alterations. Regarding the OS, only the concentrations of SP treatment showed statistical difference in relation to the NC: in L. sativa model, GSH at (C5 and C8) concentrations and LPO (C7); in A. cepa model, SOD (C3 and C4), GST (C4, C5 and C6), GSH (C5 and C8), and CAT (C3 and C7). The alterations in metabolism are possibly related to the metals, such as zinc and copper, observed in high amounts in the raw waste. The results allowed us to conclude that the raw and stabilization pond effluents offer environmental risks, requiring caution and monitoring in the use of these effluents.

Metalliferous atmospheric settleable particulate matter action on the fat snook fish (Centropomus parallelus): Metal bioaccumulation, antioxidant responses and histological changes in gills, hepatopancreas and kidneys.

Metallic smoke released by steel industries is constitute by a mixture of fine and gross particles containing metals, including the emerging ones, which sedimentation contaminates soil and aquatic ecosystems and put in risk the resident biota. This study determined the metal/metalloids in the atmospheric settleable particulate matter (SePM, particles >10 µm) from a metallurgical industrial area and evaluated metal bioconcentration, antioxidant responses, oxidative stress, and the histopathology in the gills, hepatopancreas and kidneys of fat snook fish (Centropomus parallelus) exposed to different concentrations of SePM (0.0, 0.01, 0.1 and 1.0 g L-1), for 96 h. From the 27 metals (Al, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Rb, Sr, Y, Zr, Nb, Mo, Ag, Cd, Sn, Ba, La, Ce, W, Hg, Pb, Bi) analyzed, 18 were quantified in SePM and dissolved in seawater. Metal bioconcentrations differed among organs; Fe and Zn were the metals most bioconcentrated in all organs, Fe was higher in hepatopancreas and Zn > Fe > Sr > Al was higher in kidneys. The activity of superoxide dismutase (SOD) decreased in the gills; SOD, catalase (CAT) decreased, and glutathione peroxidase (GPx) increased in hepatopancreas and, CAT, glutathione-S-transferase (GST) and the level of glutathione (GSH) increased in kidneys. The unchanged levels of lipid peroxidation and oxidized protein in any organ indicate that the antioxidant responses were efficient to avoid oxidative stress. Organ lesion indices were higher in the gills > kidneys > hepatopancreas, being higher in fish exposed to 0.01 g L-1 SePM. All changes indicate a tissue-specific metal/metalloids bioconcentration, antioxidant and morphological responses that all together compromise fish health. Regulatory normative are needed to control the emission of these metalliferous PM to preserve the environment and biota.

Ecotoxicological evaluation of water from the Sorocaba River using an integrated analysis of biochemical and morphological biomarkers in bullfrog tadpoles, Lithobates catesbeianus ().

Lithobates catesbeianus tadpoles were exposed for 96 h to water from two sites of the Sorocaba River (summer and winter), Ibiúna (PI) and Itupararanga reservoir (PIR) that contained metals. In the liver, in PI, the glutathione peroxidase (GPx) decreased, and the glutathione S-transferase (GST) and carbonyl proteins (PCO) increased. In PIR, the glutathione reduced (GSH) increased, while there was a decrease in catalase (CAT), GPx, GST, PCO, and superoxide dismutase (SOD). In winter, GPx and GST increased in both points. Regarding the kidneys, lipoperoxidation (LPO) levels and GST decreased, while GSH increased in the summer. In the winter, LPO increased in PI. In the muscle, in the summer, there was an increase in GSH and GST and change in PCO. In the winter, the levels of PCO increased and CAT decreased in PIR. The area and volume of the hepatocyte and nucleus area increased in the summer and decreased in the winter. Hepatic melanin decreased in the summer after exposure to PIR water. There were the systemic effects of Sorocaba River water exposure at different times of the year with alterations in biomarkers at different levels, in which kidney shows highest Integrated Response of Biomarkers (IBR) value followed by liver and muscle. Biochemical biomarkers were more sensitive than morphological ones. The more sensitive biochemical markers were MT, PCO, GST and LPO. These effects confirm the hypothesis of metabolic alteration in bullfrog tadpoles by the Sorocaba River water.

Multi-biomarkers approach to access the impact of novel metal-insecticide based on flavonoid hesperidin on fish.

Aquatic ecosystem health is the main concern to increasing pesticides application to control agricultural pests as it is the ultimate receptor of such materials. This study evaluated the impact of new metal-insecticide, the [Mg(hesp)2(phen)], referred as MgHP, on fish using physiological, genetic, biochemical, and morphological biomarkers. The fish, Prochilodus lineatus, was exposed to 0 (control), 1, 10, 100, 1000 µg L-1 MgHP, for 24 and 96 h. MgHP was not lethal but caused genotoxicity, altered hematological variables and, the activity of antioxidant and biotransformation enzymes and histology of liver, depending on concentration and time exposure. Hematocrit and erythrocyte number (RBC) increased without change hemoglobin content resulting in changes in hematimetric indexes after 24 h; after 96 h, only RBC was changed. Erythrocyte nuclear abnormalities and crenate cells increased after 24 h but, not after 96 h. Erythrocytes and hepatocytes indicated instability in DNA integrity however, the absence of micronuclei suggested DNA damage repairment. After 24 h, the antioxidant defense system and the phase II biotransformation enzyme was responsiveness and catalase activity decreased at high MgHP concentrations; the antioxidant response was triggered after 96 h. Hepatocyte hypertrophy, intracellular cytoplasmic substances, cytoplasm degeneration, melanomacrophage and hyperemia increased in fish exposed from 10 µg L-1 to higher MgHP concentrations; the organ alteration index increased as MgHP concentration increased showing dose-dependence. Most of hematological and genotoxic effects occurred after 24 h exposure evidencing potential recover capability of organism by activation of the antioxidant defense system and DNA repairment mechanisms. Nevertheless, the histopathological changes in the liver was maintained over time at high MgHP concentrations, a concentration usually no environmental relevant. In conclusion, this data reinforced the importance of continuing research on MgHP effects in other organisms considering the promising use of such compound to control the leaf-cutter ants and other insects.

Biochemical and morphological biomarker responses in the gills of a Neotropical fish exposed to a new flavonoid metal-insecticide.

The flavonoid metal-insecticide [Mg(hesp)2(phen)], denominated MgHP, has high potential for controlling agricultural pests. If applied in large scale, it may reach aquatic ecosystems and be harmful to the biota. This study evaluated the effects of MgHP in the gills of the Neotropical fish, Prochilodus lineatus by determining the activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione s-transferase (GST), and the levels of glutathione (GSH) and lipid peroxidation (LPO) after 24 and 96 h exposure to 0, 1, 10, 100 and 1000 µg L-1. The histopathological changes with emphases to mitochondria-rich cells (MRC) were evaluated as well. After 24 h exposure the enzyme activities and the GSH and LPO levels were unchanged however, after 96 h exposure to high MgHP concentration (1000 µg L-1), the GST activity and GSH levels increased. Oxidative stress measured as LPO levels did not occur after MgHP exposure in both periods. Gill tissue alterations increased after MgHP exposure to 10, 100 and 1000 µg L-1. Cellular atrophy, pillar cells changes, filament epithelium hyperplasia and hypertrophy, lamellar epithelium hyperplasia were the most frequent histopathology. MRC in the filament epithelium decreased after exposure to 24 h and increased after 96 h indicating possible transitory osmo-ionic disruption. P. lineatus exhibited high tolerance to MgHP. The increased GST activity and GSH levels after 96 h exposure suggested possible MgHP accumulation and concentration- and time-dependent response. Histopathology in the gills of exposed fish occurred at high MgHP concentrations. These results suggested that the MgHP into water, at high concentrations, affect the gills by changing GST activity, GSH levels and histology being useful biomarkers for MgHP water contamination.

Biochemical and genotoxic biomarkers and cell cycle assessment in the zebrafish liver (ZF-L) cell line exposed to the novel metal-insecticide magnesium-hespiridin complex.

The flavonoid metal-insecticide magnesium-hesperidin complex (MgHP) has recently been considered as a novel insecticide to replace some persistent pesticides. However, it is important to evaluate its action on non-target species, mainly those living in an aquatic environment, as these ecosystems are the final receptors of most chemicals. Reactive oxygen species, antioxidant and oxidative stress biomarkers, genotoxicity as well as cell cycle was evaluated in the liver cell line from zebrafish (Danio rerio; ZF-L) exposed to 0, 0.1, 1, 10, 100 and 1000 ng mL-1 MgHP. MgHP affected cell stability by increasing reactive oxygen species (ROS) in both exposure times (24 and 96 h) at high concentrations. Catalase (CAT) activity decreased after 24 h exposure, and glutathione and metallothionein values increased, avoiding the lipid peroxidation. Genotoxicity increased as MgHP concentration increased, after 24 h exposure, exhibiting nuclear abnormalities; it was recovered after 96 h exposure, evidencing possible stimulation of DNA repair mechanisms. The alteration in the cell cycle (increasing in the Sub-G1 phase and decreasing in the S-phase) was associated with chromosomal instability. In conclusion, the responses of ROS and the antioxidant defense system depended on MgHP concentration and time exposure, while DNA exhibited some instability after 24 h exposure, which was recovered after 96 h.

Biotransformations, Antioxidant System Responses, and Histopathological Indexes in the Liver of Fish Exposed to Cyanobacterial Extract.

Radiocystis fernandoi, a microcystin (MC) producer, has been common in cyanobacterial blooms in tropical regions. Microcystin is a hepatotoxin that causes tissue damage and even death in animals, including humans; its detoxification process may involve biotransformation and activation of the antioxidant defense system. We evaluated the detoxification pathway, examined the antioxidant defense system responses, and determined the alterations and the organ histopathological indexes in the liver of the tropical fish Hoplias malabaricus after acute and subchronic intraperitoneal exposure to microcystin. The crude microcystin extract of R. fernandoi had predominantly MC-RR and MC-YR. The detoxification process was activated by increasing ethoxyresorufin-O-deethylase activity, whereas glutathione S-transferase was inhibited. The activity of the antioxidant defense enzymes superoxide dismutase (SOD) and glutathione peroxidase decreased after acute exposure; the SOD-catalase system and the glutathione level increased after subchronic exposure. The carbonyl protein level, lipid peroxidation (LPO), and DNA damage were unchanged after acute exposure, whereas protein carbonyl was unchanged, LPO decreased, and DNA damage increased after subchronic exposure. Histopathological alteration indexes differed between acute and subchronic exposure, but the histopathological organ indexes indicate liver dysfunction in both exposure periods. We conclude that MC-RR and MC-YR induce different liver responses depending on the time of exposure, and the antioxidant defense responses after subchronic exposure may help to partially restore the liver function. Environ Toxicol Chem 2020;39:1041-1051. © 2020 SETAC.

Morphological and histopathological changes in seahorse (Hippocampus reidi) gills after exposure to the water-accommodated fraction of diesel oil.

Industrial activities and urbanization are the main sources of pollutants in estuarine environments. Diesel, which is widely used in urban and port activities, is an important source of hydrocarbons in the aquatic environment, and its water-accommodated fraction (WAF) is toxic to the local biota. This study was performed to analyze the effects of diesel oil WAF on fish. Specifically, we characterized the gill morphology of the seahorse Hippocampus reidi and analyzed the histopathological changes in the gills after exposure to 50% diesel oil WAF. Acute (12, 24, 48, and 96 h) and subchronic (168 and 336 h) toxicity tests were performed. Furthermore, a recovery protocol was conducted: after exposure to 50% WAF for 168 h, the fish were transferred and kept in seawater without contaminants for 336 h, for a total experimental period of 504 h. The seahorse branchial apparatus was found to be tufted with short filaments; the apical surfaces of the pavement cells in the filament and lamellar epithelia formed "crests" and had microridges. Mitochondria-rich cells were distributed exclusively in the lamellar epithelium, while mucous cells were distributed in the filament epithelium. All pathologies observed after acute and subchronic exposure featured progressive time-dependent alterations of lamellar structure that might disrupt gill physiological and metabolic functions. During the recovery period, the gill alterations were gradually repaired.

Osmoregulatory disturbance in Neotropical fish exposed to the crude extracts of the cyanobacterium, Radiocystis fernandoi.

Blooms of cyanobacteria, a common event in eutrophic environments, result in the release of potentially toxic substances into the water. The cyanobacterium Radiocystis fernandoi produces microcystin (MC) and other peptides that may disturb homeostasis. This study evaluated the effect of intraperitoneal injections containing the crude extract (CE) of R. fernandoi strain R28 on the gills and kidneys of neotropical fish, Piaractus mesopotamicus, 3, 6 and 24 h post-injection. CE contained MC-RR, MC-YR and minor other oligopeptides. Plasma ions and the activities of the enzymes PP1 and PP2A, Na+/K+-ATPase (NKA), H+-ATPase (HA) and carbonic anhydrase (CA) were determined and morphological changes in both the gills and kidneys were characterized. Compared to controls, the concentration of Na+ within the plasma of P. mesopotamicus decreased after treatment with CE 3 h post treatment and increased after 24 h; the concentration of K+ decreased after 6 h. The activity of the endogenous PP1 and PP2A was unchanged in the gills and was inhibited in the kidneys 6 h after i.p. injection. In the gills, NKA activity increased after 3 h and decreased 6 h post i.p. exposure. Further, NKA activity did not differ from the controls 24-h post injection. In the kidneys, NKA, HA and CA activities were unaffected by treatment. The mitochondria-rich cell (MRC) density in the gills decreased after 3 h in the filament and 3 and 6 h in the lamellae and was restored to the control levels 24 h post-exposure. Filament epithelial hyperplasia and hypertrophy, lamellar atrophy and rupture of the lamellar epithelium were the most common effects of treatment in the gills. No histopathological changes occurred in the kidneys. This study demonstrates that a single dose of toxic CE from R. fernandoi can cause a transitory ion imbalance in P. mesopotamicus which is related to the changes in MRC levels and NKA activity. Ionic balance was recovered 24 h post i.p. injection, however, morphological changes that occurred in the gills took a longer amount of time to return to normal. To conclude, the effects of components contained within the CE of R. fernandoi may be harmful to P. mesopotamicus. In particular, the recovery of ionic regulation depends on MRC responses and histopathological changes produced by CE may affect gas exchange and other gill functions.

Gill Morphology and Na+/K+-ATPase Activity of Gobionellus oceanicus (Teleostei: Gobiidae) in an Estuarine System.

Gobionellus oceanicus is a species widely distributed on the Atlantic coast and may be susceptible to anthropic effects. This study evaluated the morphology and the Na+/K+-ATPase activity of G. oceanicus gills considering the concentration of metals in the fish and Subaé River estuary. Although the metal concentrations detected in the water and sediment did not exceed certain limits, CONAMA (Brazilian Environment Council), TEL (Threshold Effect Level), and PEL (Probable Effect Level), the metals levels in gills plus muscle and skin of G. oceanicus were above the permitted setting of the Ministry of Health, Brazil. The pavement epithelial cells (PVC) of the gill filament was observed that there were long microridges either in the apical surface or in the lamella; especially, microridges degeneration was shown in some PVC from filament epithelium. The number of ionocyte and the volume density were (0.02 ± 0.001)/µm and (0.38 ± 0.27) %, respectively. The activity of Na+/K+-ATPase was 1.13 ± 0.76 µM Pi mg protein-1 h-1. We describe the volume density and number of ionocytes and Na+/K+-ATPase enzymatic activity in G. oceanicus for the first time, which is useful for basic and comparative future studies to support aquatic biomonitoring.

Reactive oxygen species and other biochemical and morphological biomarkers in the gills and kidneys of the Neotropical freshwater fish, Prochilodus lineatus, exposed to titanium dioxide (TiO2) nanoparticles.

This study investigated the action of titanium dioxide nanoparticles (TiO2-NPs), on the gills and kidneys of Neotropical freshwater fish, Prochilodus lineatus, with emphasis on reactive oxygen species (ROS) production, antioxidant responses, and morphological changes. Fish were exposed to 1, 5, 10, and 50 mg L-1 nominal TiO2-NPs suspended into water for 2 or 14 days. In gills, ROS decreased and glutathione (GSH) increased after 2 days, while ROS and GSH increased and superoxide dismutase activity decreased after 14 days. In kidneys, GSH and lipoperoxidation increased after 2 days and catalase activity decreased after 14 days. Common histopathologies in gills were epithelium hyperplasia, cellular hypertrophy, proliferation of mitochondria-rich cells (MRC), and lamellar stasis; in kidneys, there were cellular and nuclear hypertrophy, focal tubule degeneration, necrosis, and melanomacrophage (MM) proliferation. Although environmentally unlikely, high-dose exposures clarified biological effects of TiO2-NPs, such as ROS formation and MRC responses in the gills, which may impair ionic balance. It was also found that MM are likely responsible for eliminating NPs in the kidney. These findings will help to regulate TiO2-NP disposal, but longer-term studies are still needed.

Alternagin-C (ALT-C), a Disintegrin-Like Cys-Rich Protein Isolated from the Venom of the Snake Rhinocerophis alternatus, Stimulates Angiogenesis and Antioxidant Defenses in the Liver of Freshwater Fish, Hoplias malabaricus.

Alternagin-C (ALT-C) is a disintegrin-like protein isolated from Rhinocerophis alternatus snake venom, which induces endothelial cell proliferation and angiogenesis. The aim of this study was to evaluate the systemic effects of a single dose of alternagin-C (0.5 mg·kg-1, via intra-arterial) on oxidative stress biomarkers, histological alterations, vascular endothelial growth factor (VEGF) production, and the degree of vascularization in the liver of the freshwater fish traíra, Hoplias malabaricus, seven days after the initiation of therapy. ALT-C treatment increased VEGF levels and hepatic angiogenesis. ALT-C also enhanced hepatic antioxidant enzymes activities such as superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase, decreasing the basal oxidative damage to lipids and proteins in the fish liver. These results indicate that ALT-C improved hepatic tissue and may play a crucial role in tissue regeneration mechanisms.

Effects of humic acids from landfill leachate on plants: An integrated approach using chemical, biochemical and cytogenetic analysis.

Biological process treatment of landfill leachate produces a significant amount of sludge, characterized by high levels of organic matter from which humic acids are known to activate several enzymes of energy metabolism, stimulating plant growth. This study aimed to characterize humic acids extracted from landfill sludge and assess the effects on plants exposed to different concentrations (0.5, 1, 2 and 4 mM C L-1) by chemical and biological analysis, to elucidate the influence of such organic material and minimize potential risks of using sludge in natura. Landfill humic acids showed high carbon and nitrogen levels, which may represent an important source of nutrients for plants. Biochemical analysis demonstrated an increase of enzyme activity, especially H+-ATPase in 2 mM C L-1 landfill humic acid. Additionally, cytogenetic alterations were observed in meristematic and F1 cells, through nuclear abnormalities and micronuclei. Multivariate statistical analysis provided integration of physical, chemical and biological data. Despite all the nutritional benefits of humic acids and their activation of plant antioxidant systems, the observed biological effects showed concerning levels of mutagenicity.

Subchronic exposure to diflubenzuron causes health disorders in neotropical freshwater fish, Prochilodus lineatus.

The action of diflubenzuron (DFB) was evaluated in a freshwater fish, Prochilodus lineatus, after exposure to 0.06, 0.12, 0.25, or 0.50 mg L(-1) DFB for 14 days. Erythrocyte nuclear abnormalities (ENA), the gill activity of Na(+)/K(+)-ATPase, H(+)-ATPase and carbonic anhydrase (CA), and lipid peroxidation (LPO) and histopathological changes in the gills and liver were determined. The number of micronuclei increased in fish exposed to 0.25 and 0.50 mg L(-1) DFB. Plasma Cl(-) and the CA activity decreased, while the activity of Na(+)/K(+)-ATPase and of H(+)-ATPase increased in fish exposed to 0.25 and 0.50 mg L(-1) DFB. LPO did not change in the gills but increased in the liver of fish exposed to 0.25 and 0.50 mg L(-1) DFB. In the gills, histopathological changes indicated disperse lesions and slight to moderate damage in fish exposed to 0.50 mg L(-1) DFB, whereas in the liver, these changes were significantly greater in fish exposed to 0.25 and 0.50 mg L(-1) DFB, indicating moderate to severe damage. Continuous exposure to DFB is potentially toxic to P. lineatus, causing heath disorders when the fish is exposed to the two highest DFB concentrations, which are applied to control parasites in aquaculture and to control mosquito populations in the environment.

Gill dimensions in near-term embryos of Amazonian freshwater stingrays (Elasmobranchii: Potamotrygonidae) and their relationship to the lifestyle and habitat of neonatal pups

This comparative study of gill morphometrics in near-term embryos of freshwater stingray potamotrygonids examines gill dimensions in relation to neonatal lifestyle and habitat. In embryos of the potamotrygonids Paratrygon aiereba, Plesiotrygon iwamae, Potamotrygon motoro, Potamotrygon orbignyi, and cururu ray Potamotrygon sp. the number and length of filaments, total gill surface area, mass-specific surface area, water-blood diffusion distance, and anatomical diffusion factor were analysed. In all potamotrygonids, the 3rd branchial arch possessed a larger respiratory surface than the other gill arches. Larger embryos had more gill surface area and large spiracles, which are necessary to maintain the high oxygen uptake needed due to their larger body size. However, the higher mass-specific gill surface area observed in near-term embryos may be advantageous because neonates can use hypoxic environments as refuges against predators, as well as catch small prey that inhabit the same environment. As expected from their benthic mode of life, freshwater stingrays are sluggish animals compared to pelagic fishes. However, based on gill respiratory morphometry (such as gill area, mass-specific gill area, the water-blood diffusion barrier, anatomical diffusion factor, and relative opening of the spiracle), subtypes of lifestyles can be observed corresponding to: active, intermediate, and sluggish species according to Gray's scale.

Este estudo realizado com embriões a termo de arraias de água doce (Potamotrygonidae) compara e analisa as dimensões branquiais em relação ao estilo de vida e habitat dos neonatos. Nos embriões de Paratrygon aiereba, Plesiotrygon iwamae, Potamotrygon motoro, Potamotrygon orbignyi e Potamotrygon sp. (arraia cururu) foram analisados número e comprimento dos filamentos, área branquial, área superficial branquial massa-específica, barreira de difusão água-sangue e fator de difusão anatômico. Em todos os potamotrigonídeos estudados, o 3º arco branquial possui uma superfície respiratória maior que os demais arcos. Embriões de espécies de maior porte possuem grandes espiráculos e maior área de superfície branquial. Isso ajuda a manter a taxa de absorção de oxigênio proporcional ao requerimento do animal. No entanto, a grande área de superfície branquial massa-específica observadas nos embriões a termo pode ser vantajosa, pois os neonatos podem usar ambientes hipóxicos como refúgios contra predadores, bem como capturar pequenas presas que habitam o mesmo ambiente. Devido ao modo de vida bentônico, as arraias de água doce são nadadoras lentas comparadas aos peixes pelágicos. No entanto, com base na morfometria branquial (área de superfície branquial, área branquial massa-específica, barreira de difusão água-sangue, fator de difusão anatômico e abertura relativa do espiráculo), subtipos de estilos de vida podem ser observados: ativas, intermediárias e lentas, conforme escala definida por Gray.

Implications for osmorespiratory compromise by anatomical remodeling in the gills of Arapaima gigas.

The gill structure of the Amazonian fish Arapaima gigas, an obligatory air breather, was investigated during its transition from water breathing to the obligatory air breathing modes of respiration. The gill structure of A. gigas larvae is similar to that of most teleost fish; however, the morphology of the gills changes as the fish grow. The main morphological changes in the gill structure of a growing fish include the following: (1) intense cell proliferation in the filaments and lamellae, resulting in increasing epithelial thickness and decreasing interlamellar distance; (2) pillar cell system atrophy, which reduces the blood circulation through the lamellae; (3) the generation of long cytoplasmic processes from the epithelial cells into the intercellular space, resulting in continuous and sinuous paracellular channels between the epithelial cells of the filament and lamella that may be involved in gas, ion, and nutrient transport to epithelial cells; and (4) intense mitochondria-rich cell (MRC) proliferation in the lamellar epithelium. All of these morphological changes in the gills contribute to a low increase of the respiratory surface area for gas exchange and an increase in the water-blood diffusion distance increasing their dependence on air-breathing as fish developed. The increased proliferation of MRCs may contribute to increased ion uptake, which favors the regulation of ion content and pH equilibrium.

Ecotoxicity and hematological effects of a natural insecticide based on tobacco (Nicotiana tabacum) extract on Nile tilapia (Oreochromis niloticus) / Ecotoxicidade e efeitos hematológicos de um inseticida natural de extrato de tabaco (Nicotiana tabacum) em tilápia do Nilo (Oreochromis niloticus)

Natural insecticides from plant extracts represent an alternative to the highly toxic synthetic products in order to reduce environmental contamination; however some might also be toxic for non-target organisms. The present study determined the 50% lethal concentration (48h; LC50) for adults Nile tilapia (Oreochromis niloticus) exposed to the natural insecticide Fumydro®, based on the tobacco plant (Nicotiana tabacum), and evaluated its effect on hematological variables. After preliminary tests, adult specimens of O. niloticus were exposed to four Fumydro® concentrations (200, 300, 400 and 500 µL L-1). The 48h; LC50 of Fumydro® was determined at 370 ± 50 µL L-1. The surviving fish after exposure to Fumydro® showed an increase in the number of red blood cells, hemoglobin concentration, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration. The number of thrombocytes and leukocytes has not changed, unlike the differential leukocyte count that presented an increased percentage of neutrophils. The results indicated that the insecticide Fumydro® is highly toxic to Nile tilapia and changes in erythrocyte variables suggested the induction to hypoxemia with low effect on the immune system.

Inseticidas naturais produzidos a partir de extratos de plantas pode ser uma alternativa para diminuir a contaminação do ambiente por agrotóxicos sintéticos e altamente tóxicos, embora alguns deles possam também ser tóxicos para organismos não alvos. O presente estudo determinou a concentração letal 50% (CL50; 48h) para tilápia do Nilo (Oreochromis niloticus) expostas ao inseticida natural Fumydro®, produzido a base de planta de tabaco (Nicotiana tabacum) e analisou o seu efeito nas variáveis hematológicas. Após testes preliminares, exemplares adultos de O. niloticus foram expostos a quatro concentrações de Fumydro® (200, 300, 400 e 500 µL L-1). A CL50; 48h foi estimada em 370 ± 50 µL L-1. Os peixes sobreviventes a exposição ao Fumydro® apresentaram aumento no número de eritrócitos, concentração de hemoglobina, hemoglobina corpuscular média e concentração de hemoglobina corpuscular média. O número de trombócitos e de leucócitos não foi alterado, mas ocorreu alteração na contagem diferencial de leucócitos ocorrendo um aumento na porcentagem de neutrófilo nos peixes expostos a 200, 300 µL L-1 de Fumydro®. Estes resultados indicaram que o inseticida Fumydro® é extremamente tóxico para tilápia do Nilo e as alterações nas variáveis eritrocitárias sugerem que causa hipoxemia, mas tem pouca ação sobre o sistema imune.

Acute exposure of a glyphosate-based herbicide affects the gills and liver of the Neotropical fish, Piaractus mesopotamicus.

The aim of this study was to determine the acute toxicity of Roundup(®) Ready (RR) in Piaractus mesopotamicus, and evaluate the effects on the morphology of the gills and liver of exposed surviving fish. Fish were exposed to 3.0, 3.5, 4.0 and 4.5mgL(-1) of glyphosate, and the LC(50);48h was estimated at 3.74±0.2mgL(-1). Gill histopathology was rare, and the activity of Na(+)/K(+)-ATPase enzyme did not change, suggesting normal function. However, the damage to the liver was classified as moderate to severe. Cytoplasmic vacuolization, lipid accumulation, nuclear and cellular membrane alterations and glycogen depletion were found in the liver, suggesting a reduction in the liver function. The glyphosate in the RR formulation was classified as moderately toxic for P. mesopotamicus, and the severe damage in the liver may affect the detoxification and/or tissue repair process and contribute to fish death.

Functional morphology of the gill in amazonian freshwater stingrays (chondrichthyes: potamotrygonidae): implications for adaptation to freshwater.

The gill morphologies of six species of potamotrygonid freshwater stingrays from the Amazon basin were investigated using light and electron microscopy. Some unique features were found in the potamotrygonid gill: (1) fingerlike protuberances on the gill filament, (2) an Alcian blue/periodic acid-Schiff-positive histochemical reaction for several cell layers in the gill epithelium (except the basal ones), (3) pavement cells with numerous subapical mucous vesicles, (4) very large mucous cells, and (5) follicular Na(+)/K(+)-ATPase-rich (NKA-rich) mitochondria-rich cells (MRCs) in Potamotrygon sp. (known as the cururu ray). The fingerlike protuberances may constitute an additional resistance to water flow, helping to drive water through the lamellae. The secretion of a mucous substance by the pavement cells and mucous cells may help to protect the gills against mechanical injury and pathogens and aid in osmoregulation in the dilute water of the Amazon basin. All MRCs possess enfolded basolateral membranes and have poorly developed or absent tubular systems. NKA-rich MRCs are located high in the basolateral membrane. The cururu ray, which is endemic to the Rio Negro, has follicular NKA-rich MRCs (8-12 cells in cross section) that share the same apical pit in the filament; this may be considered to be an autapomorphy. The combination of these branchial characteristics may have favored tolerance to the freshwater environment during the evolution and diversification of potamotrygonids throughout the Amazon basin.